1. Field of Invention
The present invention relates to a paper feeding apparatus. More particularly, the present invention relates to a follower roller mounting mechanism for a paper feeding apparatus.
2. Related Art
Due to the increasing progress of photoelectric technology and development of business, products such as printers, scanners, photocopiers, and multi-function peripherals (MFP) have become a popular document processing apparatus widely used in not only the offices, families, and students but also in daily life.
The apparatuses such as printers, scanners, photocopiers, and MFP all have a paper feeding apparatus for feeding documents to be processed to the working area for processing. Generally speaking, the paper feeding roller set of the paper feeding apparatus has a plurality of driving rollers and follower rollers disposed at two sides of the paper feeding track. The driving rollers can be driven by external power source to feeding paper sheet. The follower rollers can be used together with the driving rollers to clamp paper sheet between the driving rollers and the follower rollers, and generate sufficient frictional force between the driving rollers and paper sheet to move the paper sheet. The follower rollers can also be disposed on the side surface of the paper feeding track alone, such that the paper sheet is prevented from directly contacting the side surface of the paper feeding track, and thus the paper sheet can be smoothly moved in the paper feeding track.
In view of the above requirements, the follower rollers must generate a normal force to the paper sheet, for generating sufficient frictional force between the driving rollers and paper to rotate the follower rollers which is driven by the paper sheet. In general, the shaft of the follower roller is loosely disposed in the base of the paper feeding apparatus, and the shaft and the follower roller are pushed by an elastic force generated by a spring. However, the follower roller mounting structure in the conventional paper feeding apparatus has a metal plate or a plastic plate mounted onto the inner side surface of the base for fixing the spring and the follower rollers, which results in a high cost and complicated assembling process.
As shown in FIG. 1, in order to eliminate the above limitations, another type of follower roller mounting structure 10 is developed. As shown in the figure, a supporting portion 11 is disposed on the paper feeding apparatus, and the supporting portion 11 has an opening 12 thereon. A shaft 13 passes through the opening 12 and is loosely disposed on the supporting portion 11. The follower roller 14 is disposed on the shaft 13, thereby contacting the driving roller (not shown) of the paper feeding apparatus. A spring 15 is fixed below the shaft 13 and presses against the shaft 13, so as to provide a normal force to the shaft 13, making the follower roller 14 contacts the driving roller.
However, as the spring 15 is fixed below the shaft 13, the shaft 13 must be detached before mounting or detaching the spring 15, which results in that the follower roller mounting structure 10 cannot be easily and quickly mounted or detached, thus reducing the assembling speed, increasing the time required for repairing, and increasing the cost of manufacturing.
Also, as the mounting position of the spring 15 in the conventional follower roller mounting structure 10 cannot be adjusted, the normal force generated by the spring mostly acts in ineffective direction, and thus the spring performance is not good. Due to uneven force applied to the shaft 13, the normal force generated by the follower roller 14 and being applied to the paper sheet is insufficient, and the follower roller 14 cannot be driven by the paper sheet to rotate and even sliding friction exists between the follower roller 14 and the paper sheet, and thus paper jam may occur or the paper sheet may be wrinkled.